Portable lighting unit



FIG. 1 is a front perspective view showing the new design, with the broken line showing for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a side elevation view thereof, the opposite side being a mirror image;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front elevation view thereof; and,

FIG. 6 is a rear elevation view thereof. 

The ornamental design for a portable lighting unit, as shown and described. 